| Vinyl chloride (CH2=CHCL, VC) is widely used in industry, almost95%used in the polymerization to polyvinyl chloride (PVC). China is one of the important PVC production countries, and its annual production accounts for about50%of the global production, so the health of VC exposed workers should be paid more attention.VC exposure has been associated with hepatic angiosarcoma (ASL) and hepatocellular cancer, and was classified as a group1carcinogen by IARC in1987. Recent epidemiological studies have shown VC is a multi-organ and multi-stystem carcinogen. It has caused great concern to people who may be exposed to it. To avoid the potential health hazard, many countries have developed some techniques to make a great progress in reducing exposure concentration of VC. At present, the permissible exposure limit (PEL) of VC in developed countries is1ppm (2.79mg/m3), and the permissible concentration-time weighted average (PC-TWA) in China is10mg/m3. So it is necessary to analyze occupational health effects in VC-exposed workers whose exposure level was several times higher than the occupational health standard in developed countries.In order to explore effect biomarkers under low level VC exposure, this study evaluated the relationship between the cumulative exposure dose and VC-induced chromosome damage, immunologic function in VC-exposed group (95individuals:male73and female22), comparing with the control group (32individuals:male18and female14) in a chemical company in Shanghai.Cytokinesis-block micronueleus (CB-MN) assay was used to detect chromosome damage of the peripheral blood lymphocyte in VC-exposed workers. The results showed that the frequency of micronucleus in VC-exposed groups(3.19±1.76)%o were significantly higher than the control group (1.91±1.36)%o (FR=1.67(95%CI1.27-2.20), p<0.001). So the frequency of CB-MN of peripheral blood lymphocyte can be used as an effect biomarker under low level VC exposure. Moreover, multiple Poisson regression analysis showed that a significant increase of micronucleus occurred with age and smoking, when occupation ally exposed. When the confounding factors were adjusted, the MN frequency of subjects with elder age (>35) were higher than lower age (≤35)groups (FR=1.49(95%CI1.17-1.89), P＜0.001). The MN frequency of subjects with smoking were lower than unsmoking groups (FR=0.79(95%CI0.63-0.99), p<0.001). The MN frequency of VC-exposed were higher than control group (FR=1.69(95%CI1.29-2.22),p<0.001).Enzyme-linked immunosorbent assay (ELISA) was used to detect immunologic function of the blood serum from the subjects. The results showed that the expressions of IgG, IgM of VC-exposed group were significantly higher than those of the control group.Moreover, multiple linear regression analysis showed that a significant different of immunoglobins occurred with drinking, when occupationally exposed. When the confounding factors were adjusted, the expressions of IL-6、IgG、IgM of VC-exposed group were higher than those of the control group (P<0.05). The expression of IgM of subjects with drinking were higher than non drinkinging subjects (p<0.05).TNF-α, IgM were significantly correlated with chromosomal damage of low exposure group (r=1.00,p<0.05). IFN-y were significantly correlated with chromosomal damage of high exposure group (r=0.79, p<0.05). The results suggested that TNF-α, IgM, IFN-γ may play a some role in chromosal damage induced by VC.In conclusion, VC can alter expressions of immunoglobins and induce chromosome damage even when the exposure level is lower than the national occupational health standard of China. Therefore, the frequency of MN of peripheral blood lymphocyte can be used as an effective and sensitive biomarker for chromosome damage and follow up under low-level VC exposure. The immunoglobin may be used as an effect biomarkers in the regular health surveillance of VC-exposed workers. The expression of immunoglobin may play a some role in chromosal damage induced by VC-exposed. |
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